To effect the lowering and raising of long strings of oil well casing, it is conventional to employ an elongated spider which is open at the center to permit the well casing to be moved rapidly through the central opening of the spider, while operations are proceeding normally but which will permit the firm grasp of the casing when required as during an emergency. Conventionally, a plurality of arcuate wedge shaped sector like elements or slips formed of cast metal such as steel are borne by a spider bowl which is hollow and whose interior surface tapers upwardly and outwardly, upon which are carried the slips. The slips ride on the tapered surface of the spider bowl, being normally keyed thereto and means are provided for simultaneously raising and lowering the slips in contact with the tapered surface of the hollow spider bowl such that, when the slips are raised, they also move radially away from each other to increase the size of the opening defined by the slips through which passes the well casing.
One such type of well spider is shown in U.S. Pat. No. 2,274,273 issuing Feb. 24, 1972, to Earl J. Miller.
While the well spider of that construction functions adequately to perform its given task, it is necessary to physically shift the spider between extreme vertical heights with respect to the well casing, normally requiring the unit to be raised above the upper end of the well casing or well casing section to be grasped, prior to lowering the spider into a position where, when needed, the slips may be shifted on their keyways relative to the bowl and the spider base member to frictionally grasp the periphery of the well casing projecting therethrough. Further, the mechanical actuating and slip interior section mechanism is generally out of direct access.
It is, therefore, a primary object of the present invention to provide an improved oil well casing spider which can be quickly positioned with respect to the oil casing without the necessity of vertically raising the spider above the casing and which can be moved into casing encompassing position at any desired vertical level with respect to the casing in question.
It is a further object of the present invention to provide an improved well spider of this type in which the spider may be moved laterally relative to the well casing to effect the surrounding of the well casing by the slips carried by the well spider without the necessity of modifying or removing the mechanism carried by the spider base member for achieving relative movement between the slips and the hollow bowl supporting the same.